Communications device and method

ABSTRACT

A mobile communications system transmitting/receiving data to/from communications devices includes one or more base stations, each including a transmitter and receiver. The transmitter and receiver provide a wireless access interface communicating data to/from the communications devices. The wireless access interface provides plural communications resource elements across a first frequency range and within a second frequency range within and smaller than the first frequency range. The wireless access interface includes plural time divided sub-frames, at least one of the sub-frames including a first wideband control channel in a first part of each sub-frame communicating first signalling information, and a second narrow band control channel in a second part of each sub-frame. The base stations transmit a sleep indication signal to one or more of the communications devices, to realize a power saving to the communications devices which are not to receive the second signalling information for one or more sub-frames.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to British Patent Application1216037.0, filed in the UK IPO on 7 Sep. 2012, the entire contents ofwhich being incorporated herein by reference.

TECHNICAL FIELD OF THE DISCLOSURE

The present disclosure relates to communications devices, and methods ofcommunicating using mobile communications devices.

BACKGROUND OF THE DISCLOSURE

Mobile communications systems continue to be developed to providewireless communications services to a greater variety of electronicdevices. In more recent years, third and fourth generation mobiletelecommunication systems, such as those based on the 3GPP defined UMTSand Long Term Evolution (LTE) architectures have been developed tosupport more sophisticated communications services to personal computingand communications devices than simple voice and messaging servicesoffered by previous generations of mobile telecommunication systems. Forexample, with the improved radio interface and enhanced data ratesprovided by LTE systems, a user may enjoy high data rate applicationssuch as mobile video streaming and mobile video conferencing that wouldpreviously only have been available via a fixed line data connection.The demand to deploy third and fourth generation networks is thereforestrong and the coverage area of these networks, i.e. geographiclocations where access to the networks is possible, is expected toincrease rapidly.

More recently it has been recognised that rather than providing highdata rate communications services to certain types of electronicsdevices, it is also desirable to provide communications services toelectronics devices that are simpler and less sophisticated. Forexample, so-called machine type communication (MTC) applications may besemi-autonomous or autonomous wireless communication devices which maycommunicate small amounts of data on a relatively infrequent basis. Someexamples include so-called smart meters which, for example, are locatedin a customer's house and periodically transmit information back to acentral MTC server data relating to the customer's consumption of autility such as gas, water, electricity and so on.

Whilst it can be convenient for a communications device such as an MTCtype device to take advantage of the wide coverage area provided by athird or fourth generation mobile telecommunication network there are atpresent disadvantages. Unlike a conventional third or fourth generationcommunications device such as a smartphone, an MTC-type device ispreferably relatively simple and inexpensive. The type of functionsperformed by the MTC-type device (e.g. collecting and reporting backdata) do not require particularly complex processing to perform.

As will be appreciated, there may be a desire for many types ofcommunications devices to conserve power. However this may beparticularly applicable to MTC type devices, which are arranged tooperate with a less sophisticated transceiver and may for example be lowpower and battery operated and for example may be deployed for asignificant time before the batteries are to be replaced. Accordinglythere is a desire to provide arrangements in which a power of all typesof communications devices operating with a mobile communicationsnetworks can be conserved.

SUMMARY OF THE DISCLOSURE

According to a first aspect of the present disclosure there is provideda mobile communications system for transmitting data to and/or receivingdata from communications devices. The mobile communications systemincludes one or more base stations, each of which includes a transmitterand a receiver, which are configured to provide a wireless accessinterface for communicating data to and/or from the communicationsdevices. The wireless access interface provides a plurality ofcommunications resource elements across a first frequency range. Thewireless access interface includes a plurality of time dividedsub-frames, which may for example include some or all of the pluralityof communications resource elements of the first frequency range. Atleast one of the sub-frames includes a first wideband control channel ina part of the sub-frame for communicating first signalling informationto one or more of the communications devices, and at least one of thesub-frames includes a second narrow band control channel in a secondpart of the sub-frame and having a bandwidth which is less than thefirst wideband control channel and a duration of the second narrow bandcontrol channel within the sub-frame is greater than a duration of thefirst wideband control channel within the sub-frame. The second narrowband control channel is configured for communicating second signallinginformation to one or more of the communications devices. The basestations are configured to transmit a sleep indication signal to one ormore of the communications devices, the sleep indication signalindicating to the one or more of the communications devices that thecommunications devices do not need to receive the second signallinginformation from the second narrow band control channel. Accordingly apower saving to the communications devices which are not to receive thesecond signalling information for one or more sub-frames can beprovided.

It is currently being proposed to provide mobile communications systems,such as LTE for example, in which a plurality of sub-carriers aredivided in time to provide sub-frames. Each sub-frame may include a wideband control channel region for transmitting a control channel forcommunicating signalling information such as for example granting accessto shared communications resources. Each sub-frame may also include atleast one narrow band control channel region which has a narrowerbandwidth than the wide band control channel region but has a longertime duration and can be used to transmit a further control channel tocommunicate the same information or different information for the samepurpose as the control channel information communicated on the wide bandcontrol channel. The narrow band control channel region may for examplehave a duration which extends over substantially all of the remainder ofa sub-frame after the wide band control channel region.

Embodiments of the present disclosure can provide an arrangement inwhich a mobile communications network is configured to provide awireless access interface which includes a first wide band controlchannel and a second narrow band control channel Signalling informationsuch as resource allocation messages for accessing shared resources ofthe wireless access interface may be communicated via either the firstwide band communications channel or the second narrow bandcommunications channel, or both. If there is a class of devices which isonly able to receive resource allocation messages via the second narrowband communications channel then because this narrow band controlchannel needs to convey similar information to the wide bandcommunications channel then it may be arranged to have a longer durationin time. However, if the narrow band communications channel is arrangedto communicate signalling information to particular communicationsdevices, such as for example, resource allocation messages, then acommunications device must be arranged to receive the signalstransmitted throughout the narrow band control channel, only then todetermine that the signalling information is not for that communicationsdevice. For example resource allocation message are directed to acommunications device to which the communications resources of theshared channels are being allocated. If a communications device isrequired to receive the signalling information from the narrow bandcontrol channel only then to discover that the resources are notallocated to that communications device then the communications devicewould have had to power at least some part of its receiver for aduration of the narrow band control channel. The narrow band controlchannel could stretch over a substantial part of the sub-frame, which isthe case for example of LTE, in which an Enhanced Physical DownlinkControl Channel (EPDCCH) may form such a narrow band control channelafter a first wide band control channel, which in the example of LTE isa Physical Downlink Control Channel (PDCCH). The communications devicemust therefore maintain power to at least some part of its receiver inorder to receive the signalling information from the narrow bandcommunications channel. However if the communications device thendiscovers that the signalling information is not for the communicationsdevice then it will have wasted power.

Embodiments of the present disclosure have been devised in recognitionthat communications devices do not need to receive signallinginformation via a narrow band communications channel if the signallinginformation is not directed to the communications device. Accordingly,embodiments of the present disclosure provide an arrangement fortransmitting a sleep indication signal to one or more communicationsdevices which are not to receive signalling information in a narrow bandcommunications channel for one or more sub-frames. In one example bytransmitting the sleep indication signal early in a sub-frame,indicating that one or more of the communications devices do not need toreceive the signalling information from the narrow band communicationschannel of the sub-frame, then these one or more communications devicescan suspend or at least reduce the power to at least part of theirreceivers for at least some part of the sub-frame thereby saving power.

Alternatively the sleep indication signal could include an indication ofone or more of the communications devices which are to receivesignalling information in the second narrow band control channel, sothat if a communications devices determines that its identifier is notpresent in the sleep indication signal then there is no signallinginformation in the second narrow band control channel and it can reducepower to at least part of its receiver.

As will be appreciated by those familiar with mobile communicationssystems such as LTE, data is communicated as packets via a wirelessaccess interface, so that resources are not allocated to acommunications device unless and until that communications device is toreceive data on the downlink or transmit data on the uplink. Furthermorethe communications device may be moved to an inactive, idle or sleepstate in which it is currently inactive in that there are nocommunications services being required. However when in an active statethe mobile may receive resource allocation messages once acommunications session has been established with the network.Accordingly, when in an active state, packets may be communicated atnon-regular intervals, because a scheduler in the base station or othernetwork element may not have sufficient capacity to transmit or receivedata from a communications device every sub-frame even when data is tobe transmitted or received. As such in some examples, resourceallocation messages are communicated in a control channel to allocateresources to the communications devices within a sub-frame on asub-frame basis. Accordingly by communicating a sleep indication signal,the communications device may enter a sleep state for at least some partof the sub-frame, as distinct from a sleep state in which thecommunications device is inactive.

Various further aspects and embodiments of the disclosure are providedin the appended claims, including but not limited to, a mobilecommunications system network element for communicating data to and/orfrom mobile communications devices, used in a mobile communicationsnetwork and a method of communicating data to and/or from mobilecommunications devices in a mobile communications system.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure will now be described by way ofexample only with reference to the accompanying drawings in which likeparts are provided with corresponding reference numerals and in which:

FIG. 1 provides a schematic diagram illustrating an example of aconventional mobile communications system;

FIG. 2 provides a schematic diagram illustrating a conventional LTEdownlink radio frame;

FIG. 3 provides a schematic diagram illustrating a conventional LTEdownlink radio sub-frame;

FIG. 4 provides a schematic diagram illustrating an LTE downlink radiosub-frame in which a virtual carrier has been inserted;

FIG. 5 provides a schematic diagram illustrating an example of twosuccessive LTE downlink radio sub-frames which are arranged to provide avirtual carrier including communications resources within a bandwidthwhich is narrower than a bandwidth of a host system;

FIG. 6 provides a schematic diagram illustrating an example of an LTEdownlink radio sub-frame which includes a narrow band control channel;

FIG. 7a provides a schematic diagram illustrating an example of an LTEdownlink radio sub-frame in which a virtual carrier is provided andincludes a narrow band control channel in accordance with an exampleembodiment; and FIG. 7b presents an illustrative schematic diagram ofpart of the example of FIG. 7a in an expanded view;

FIG. 8 provides a schematic diagram illustrating an example of an LTEdownlink radio sub-frame in which a virtual carrier is provided andincludes a narrow band control channel which is distributed between twoparts of a virtual carrier in accordance with an example embodiment;

FIG. 9 provides a schematic diagram illustrating an example of an LTEdownlink radio sub-frame in which a virtual carrier is provided andincludes a narrow band control channel in accordance with an exampleembodiment;

FIG. 10 provides a schematic diagram illustrating an example of an LTEdownlink radio sub-frame in which a virtual carrier is provided andincludes a narrow band control channel in accordance with an exampleembodiment;

FIG. 11 provides a schematic diagram showing part of an adapted LTEmobile telecommunication network arranged in accordance with an exampleof the present disclosure; and

FIG. 12 is an illustrative flow diagram according to an exampleembodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS Conventional Network

FIG. 1 provides a schematic diagram illustrating the basic functionalityof a conventional mobile communications system.

The network includes a plurality of base stations 101 connected to acore network 102. Each base station provides a coverage area 103 (i.e. acell) within which data can be communicated to and from communicationsdevices 104. Data is transmitted from a base station 101 to acommunications device 104 within a coverage area 103 via a radiodownlink. Data is transmitted from a communications device 104 to a basestation 101 via a radio uplink. The core network 102 routes data to andfrom the base stations 104 and provides functions such asauthentication, mobility management, charging and so on.

The term communications devices will be used to refer to acommunications terminal or apparatus which can transmit or receive datavia the mobile communications system. Other terms may also be used forcommunications devices such as communications terminal, remote terminal,transceiver device or user equipment (UE) which may or may not bemobile.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division multiplex (OFDM) based radio accessinterface for the radio downlink (so-called OFDMA) and the radio uplink(so-called SC-FDMA). Data is transmitted on the uplink and on thedownlink on a plurality of orthogonal sub-carriers. FIG. 2 shows aschematic diagram illustrating an OFDM based LTE downlink radio frame201. The LTE downlink radio frame is transmitted from an LTE basestation (known as an enhanced Node B) and lasts 10 ms. The downlinkradio frame comprises ten sub-frames, each sub-frame lasting 1 ms. Aprimary synchronisation signal (PSS) and a secondary synchronisationsignal (SSS) are transmitted in the first and sixth sub-frames of theLTE frame, in the case of frequency division duplex (FDD) system. Aphysical broadcast channel (PBCH) is transmitted in the first sub-frameof the LTE frame. The PSS, SSS and PBCH are discussed in more detailbelow.

FIG. 3 provides a schematic diagram providing a grid which illustratesthe structure of an example of a conventional downlink LTE sub-frame.The sub-frame comprises a predetermined number of symbols which aretransmitted over a 1 ms period. Each symbol comprises a predeterminednumber of orthogonal sub-carriers distributed across the bandwidth ofthe downlink radio carrier.

The example sub-frame shown in FIG. 3 comprises 14 symbols and 1200sub-carriers spaced across a 20 MHz bandwidth. The smallest unit onwhich data can be transmitted in LTE is twelve sub-carriers transmittedover one sub-frame. For clarity, in FIG. 3, each individual resourceelement is not shown, but instead each individual box in the sub-framegrid corresponds to twelve sub-carriers transmitted on one symbol.

FIG. 3 shows resource allocations for four LTE devices 340, 341, 342,343. For example, the resource allocation 342 for a first LTE device (UE1) extends over five blocks of twelve sub-carriers, the resourceallocation 343 for a second LTE device (UE2) extends over six blocks oftwelve sub-carriers and so on.

Control channel data is transmitted in a control region 300 of thesub-frame comprising the first n symbols of the sub-frame where n canvary between one and three symbols for channel bandwidths of 3 MHz orgreater and where n can vary between two and four symbols for channelbandwidths of 1.4 MHz. The data transmitted in the control region 300includes data transmitted on the physical downlink control channel(PDCCH), the physical control format indicator channel (PCFICH) and thephysical HARQ indicator channel (PHICH).

The PDCCH contains control data indicating which sub-carriers on whichsymbols of the sub-frame have been allocated to specific LTE devices.Thus, the PDCCH data transmitted in the control region 300 of thesub-frame shown in FIG. 3 would indicate that UE1 has been allocated thefirst block of resources 342, that UE2 has been allocated the secondblock of resources 343, and so on. In sub-frames where it istransmitted, the PCFICH contains control data indicating the duration ofthe control region in that sub-frame (i.e. between one and four symbols)and the PHICH contains HARQ (Hybrid Automatic Request) data indicatingwhether or not previously transmitted uplink data has been successfullyreceived by the network.

In certain sub-frames, symbols in a central band 310 of the sub-frameare used for the transmission of information including the primarysynchronisation signal (PSS), the secondary synchronisation signal (SSS)and the physical broadcast channel (PBCH). This central band 310 istypically 72 sub-carriers wide (corresponding to a transmissionbandwidth of 1.08 MHz). The PSS and SSS are synchronisation signals thatonce detected allow the LTE device 104 to achieve frame synchronisationand determine the cell identity of the enhanced Node B transmitting thedownlink signal. The PBCH carries information about the cell, comprisinga master information block (MIB) that includes parameters that the LTEdevices require to access the cell. Data transmitted to individual LTEdevices on the physical downlink shared channel (PDSCH) can betransmitted in the remaining blocks of communications resource elementsof the sub-frame. Further explanation of these channels is provided inthe following sections.

FIG. 3 also shows a region of PDSCH containing system information andextending over a bandwidth of R₃₄₄.

The number of sub-carriers in an LTE channel can vary depending on theconfiguration of the transmission network. Typically this variation isfrom 72 sub carriers contained within a 1.4 MHz channel bandwidth to1200 sub-carriers contained within a 20 MHz channel bandwidth as shownin FIG. 3. As is known in the art, data transmitted on the PDCCH, PCFICHand PHICH is typically distributed on the sub-carriers across the entirebandwidth of the sub-frame. Therefore a conventional LTE device must beable to receive the entire bandwidth of the sub-frame in order toreceive and decode the control region.

Virtual Carrier

Certain classes of devices, such as MTC devices (e.g. semi-autonomous orautonomous wireless communication devices such as smart meters asdiscussed above), support communication applications that arecharacterised by the transmission of small amounts of data at relativelyinfrequent intervals and can thus be considerably less complex thanconventional LTE devices. Communications devices may include ahigh-performance LTE receiver unit capable of receiving and processingdata from an LTE downlink frame across the full carrier bandwidth.However, such receiver units can be overly complex for a device whichonly needs to transmit or to receive small amounts of data. This maytherefore limit the practicality of a widespread deployment of reducedcapability MTC type devices in an LTE network. It is preferable insteadto provide reduced capability devices such as MTC devices with a simplerreceiver unit which is more proportionate with the amount of data likelyto be transmitted to the device. Furthermore, as explained above it isdesirable to include features in a mobile communications network and/orcommunications devices which can conserve power consumption of thecommunications devices.

In conventional mobile telecommunication networks, data is typicallytransmitted from the network to the communications devices in afrequency carrier (first frequency range) where at least part of thedata spans substantially the whole of the bandwidth of the frequencycarrier. Normally a communications device cannot operate within thenetwork unless it can receive and decode data spanning the entirefrequency carrier, i.e. a maximum system bandwidth defined by a giventelecommunication standard, and therefore the use of communicationsdevices with reduced bandwidth capability transceiver units isprecluded.

However, as disclosed in co-pending International patent applicationsnumbered PCT/GB2012/050213, PCT/GB2012/050214, PCT/GB2012/050223 andPCT/GB2012/051326, the contents of which are herein incorporated byreference, a subset of the communications resource elements comprising aconventional carrier (a “host carrier”) are defined as a “virtualcarrier”, where the host carrier has a certain bandwidth (firstfrequency range) and where the virtual carrier has a reduced bandwidth(second frequency range) compared to the host carrier's bandwidth. Datafor reduced capability devices is separately transmitted on the virtualcarrier set of communications resource elements. Accordingly, datatransmitted on the virtual carrier can be received and decoded using areduced complexity or capability transceiver unit.

Devices provided with reduced complexity or capability transceiver units(hereafter referred to as “reduced capability devices”) could operate byusing a part of its full capability (i.e. reduced capability set of itsfull capability) or they could be constructed to be less complex andless expensive than conventional LTE type devices (onwards referred togenerally as LTE devices). Accordingly, the deployment of such devicesfor MTC type applications within an LTE type network can become moreattractive because the provision of the virtual carrier allowscommunications devices with less expensive and less complex transceiverunits to be used.

FIG. 4 provides a schematic diagram illustrating an LTE downlinksub-frame which includes a virtual carrier inserted in a host carrier.

In keeping with a conventional LTE downlink sub-frame, the first nsymbols (n is three in FIG. 4) form the control region 300 which isreserved for the transmission of downlink control data such as datatransmitted on the PDCCH. However, as can be seen from FIG. 4, outsideof the control region 300 the LTE downlink sub-frame includes a group ofcommunications resource elements below the central band 310 which form avirtual carrier 501. The virtual carrier 501 is adapted so that datatransmitted on the virtual carrier 501 can be treated as logicallydistinct from the data transmitted in the remaining parts of the hostcarrier and can be decoded without first decoding all the control datafrom the control region 300. Although FIG. 4 shows the virtual carrieroccupying frequency resources below the centre band, in general thevirtual carrier can alternatively either occupy frequency resourcesabove the centre band or frequency resources including the centre band.If the virtual carrier is configured to overlap any resources used bythe PSS, SSS or PBCH of the host carrier, or any other signaltransmitted by the host carrier that a communications device operatingon the host carrier would require for correct operation and expect tofind in a known pre-determined location, the signals on the virtualcarrier can be arranged such that these aspects of the host carriersignal are maintained.

As can be seen from FIG. 4, data transmitted on the virtual carrier 501is transmitted across a limited bandwidth. This could be any suitablebandwidth providing it is smaller than that of the host carrier. In theexample shown in FIG. 4 the virtual carrier is transmitted across abandwidth comprising 12 blocks of 12 sub-carriers (i.e. 144sub-carriers) which is equivalent to a 2.16 MHz transmission bandwidth.Accordingly, a device receiving data transmitted on the virtual carrierneed only be equipped with a receiver capable of receiving andprocessing data transmitted over a bandwidth of 2.16 MHz. This enablesreduced capability devices (for example MTC type devices) to be providedwith simplified receiver units yet still be able to operate within anOFDM type communication network which, as explained above,conventionally requires devices to be equipped with receivers capable ofreceiving and processing an OFDM signal across the entire bandwidth ofthe signal.

As explained above, in OFDM based mobile communication systems such asLTE, downlink data is dynamically assigned to be transmitted ondifferent sub-carriers on a sub-frame by sub-frame basis. Accordingly,in every sub-frame the network must signal which sub-carriers on whichsymbols contain data relevant to which devices (i.e. downlink resourceallocation signalling).

As can be seen from FIG. 3, in a conventional downlink LTE sub-framethis information is transmitted on the PDCCH during the first symbol orsymbols of the sub-frame. However, as previously explained, theinformation transmitted in the PDCCH is spread across the entirebandwidth of the sub-frame and therefore cannot be received by a mobilecommunication device with a simplified receiver unit capable only ofreceiving the reduced bandwidth virtual carrier.

Accordingly, as can be seen in FIG. 4, some symbols of the virtualcarrier can be reserved as a virtual carrier control region 502 which isallocated for the transmission of signalling information, which can beresource allocation messages indicating which communications resourceelements of the virtual carrier 501 have been allocated. In someexamples the number of symbols comprising the virtual carrier controlregion 502 can be fixed.

The virtual carrier control region can be located at any suitableposition within the virtual carrier for example in the first few symbolsof the virtual carrier. In a further example, the virtual carriercontrol symbols may reference virtual carrier PDSCH transmissions in aseparate sub-frame.

FIG. 5 provides a simplified arrangement to the virtual carrierconfiguration shown in FIG. 4 for two consecutive sub-frames n, n+1 320,321. As for the example shown in FIG. 4 resource allocation messages canbe communicated via the host control region 300 which corresponds to thePDCCH for allocating resources of the host shared channel which is thePDCCH 540 to full bandwidth capable communications devices. For thesimplified example shown in FIG. 5, a virtual carrier 501 is shownapproximately in a central region of the frequency band width of thehost system. As explained above, a virtual carrier control region 502 isshown for allocating resources which are shared amongst the reducedcapability devices. Thus, the virtual carrier control region 502transmits resource allocation messages to the communications devices 104allocating communications resources of the virtual carrier PDSCH 540from within the frequency range corresponding to the virtual carrier501.

In FIG. 5 the control region 300 is shown in a corresponding position tothat in which it appears in FIG. 4 and may be in one example the PDCCHwhich communicates messages to communications devices allocatingcommunications resources which are shared by communications devices. Inorder to receive the messages, a communications device 104 needs to havea receiver unit which can receive signals transmitted across the fullfrequency range of the PDCCH 300.

Narrow Band Control Channel

It has been proposed, for example for LTE systems to provide a narrowband control channel region within a sub-frame together with a wide bandcontrol channel region because the wide band control channel regiontypically exists in the same part of the sub-frame of a wireless accessinterface and across all sub-carriers in the frequency band of the hostcarrier. The wide band control channel region may correspond to thePDCCH 300 in the example of LTE. Accordingly, it is possible that twobase stations of neighbouring cells are transmitting different controlchannel information in the wide band control channel regioncontemporaneously which could, therefore interfere with each other. Byproviding a narrow band control channel region within each sub-framewhich can be in a different location in frequency in the neighbouringcells, covering a different set of sub-carriers, for example, thensignalling information can be communicated to communications deviceswithin different cells with a reduced potential for causing co-channelinter-cell interference. Furthermore beam forming techniques can beapplied to signals transmitted or received on the narrow band controlchannel Such an arrangement for example for LTE is being proposed in3GPP.

As shown in FIG. 6 a narrow band control channel region 600 is alsoprovided, which for the example of LTE could contain the EPDCCH 600. Thenarrow band control channel 600 communicates among other things resourceallocation messages to communications devices. However, the narrow bandcontrol channel region 600 is narrower in frequency than the wide bandcontrol channel region 300 and extends for substantially the entiresub-frame after the transmission of the wide band control channel 300.As shown in the example of FIG. 6, the narrow band control channel 600is formed within a virtual carrier region 501. Thus in one example thenarrow band control channel 600 could be the EPDCCH and the wide bandcontrol channel could be the PDCCH 300 although the skilled person willappreciate that these are just examples of respective wide band andnarrow band control channels, which are applicable for the LTE example.

Sleep Indication Signal (SIS)

As explained above, embodiments of the present disclosure can provide anarrangement for communicating a sleep indication signal to one or morecommunications devices to indicate that these one or more communicationsdevices do not need to detect and recover signalling informationcommunicated in the narrow band control channel, which in one example isthe EPDCCH. Such an arrangement is shown in FIGS. 7a and 7 b.

FIG. 7a corresponds to the example illustrated in FIG. 6. In FIGS. 7aand 7b , a sleep control channel 700 is provided for communicating asleep indication signal (SIS) to one or more mobile communicationsterminals which are identified as not being allocated communicationsresources within one or more sub-frames. As will be appreciated in orderto conserve power communications devices which are not to be allocatedshared communications resources can power down at least part of theirreceivers. To inform these communications devices to power down at leastpart of their receivers, the SIS should be provided before or as soon aspossible after the communications devices attempt to detect signallinginformation from the narrow band control channel. Accordingly, and asshown in FIG. 7a the sleep control channel 700 is disposed substantiallyat the start of the narrow band control channel 600 and may provide a‘sleep’ indication for that sub-frame.

An example arrangement for the allocation of the sleep control channel700 is shown in more detail in FIG. 7b . In FIG. 7b , two resourceblocks 720, 722 each comprising twelve communications resource elementsare shown. The narrow band control channel 600 is shown alongside sharedcommunications resources 540 which are allocated to the virtual carrierand therefore form part of the (second) frequency range allocated to thevirtual carrier.

As will be appreciated, whilst the above explanation has been providedin respect of receiving signals on the down-link, the resourceallocations transmitted on control channels may be of communicationsresources for up-link transmissions by the communications devices to themobile communications network.

As explained above, for an example in which the narrow band controlchannel region is used for a virtual carrier application with reducedcapability devices, a reduced capability receiver, being strictlynarrowband, is not able to receive signalling information from the hostcarrier PDCCH. As such it is not currently possible to implement amicro-sleep functionality in which communication devices not using thenarrow band control channel region 600 but using only the wide bandcontrol channel region 300 can go into sleep mode during the sub-framefollowing the wide band control channel region 300, when there is nocontrol information for the communication devices in the wide bandcontrol channel region 300. As a result, all reduced capabilitycommunications devices must process the whole of every sub-frame eventhough they may in at least some sub-frames have no uplink or downlinktransmissions scheduled by the signalling information. The receive powerconsumption and signal processing effort in such sub-frames could bewasted for potentially many reduced capability communications devices.For MTC devices, which are expected to operate with low powerconsumption, limited battery capacity and yet very long life, it isdesirable to minimise such wasted power. The SIS could be embedded intoa limited resource available for the narrow band control channel regionwhilst still leaving enough space for the actual DCI messages formultiple communications devices to be transmitted.

Embodiments may therefore be arranged to embed a very small amount ofinformation at the start of an EPDCCH-like virtual carrier controlregion (narrow band control channel region), to instruct certaincommunications devices that they may cease processing the remainder ofthe sub-frame. Since the narrow band control channel region is likely tooperate in highly restricted resources, this SIS must be expressed verycompactly whilst still preferably allowing multiple communicationsdevices to receive the SIS in a sub-frame.

As shown in the example embodiment of FIG. 7a at the beginning of thenarrow band control region 600 an SIS is embedded to convey the identityof at least one communications device for which there is no downlink oruplink resource assignment in the present sub-frame. As suchcommunications devices may try to decode the SIS in which the identityis conveyed and, if they find themselves identified there, may abandonprocessing the rest of the sub-frame.

In one example structure of the SIS, the virtual carrier will be in theminimum permitted LTE bandwidth of 1.4 MHz, or 6 RBs. The virtualcarrier begins after the wide band control region 300, which is variablein width per sub-frame, or the virtual carrier is operating on a carrierwith no control region, such as may transpire in future on a New CarrierType. It is desirable to minimise the control overhead in suchrestricted resource, so in one example the narrow band control channelregion is just 1 RB wide, positioned anywhere contiguously within thevirtual carrier. Illustratively, the narrow band control channel regionmay occupy both slots of the sub-frame, but this is just one example. Itis further desirable to minimise the resource occupied by the SIS, so inone example the SIS is arranged to occupy a single OFDM symbol, andtherefore twelve resource elements. Keeping the format of PDCCH andEPDCCH, it is assumed that the SIS uses QPSK modulation for robustness.Therefore, there is a maximum of 24 bits available to implement SIS.This arrangement is summarised in FIG. 7 (b) which shows an expandedrepresentation on just the first two resource blocks of the virtualcarrier, but as will be appreciated this is one example only.

As will be appreciated a mobile communications device 104 which receivesan SIS from the sleep control channel 700 will power down at least partof its receiver therefore avoiding having to recover signallinginformation from the narrow band control channel 600 which extends overthe entire length of the sub-frame. Therefore in a typical arrangementin which the narrow band control channel communicates resourceallocation messages to communications devices to allocate resources ofthe shared channel 540 for a subsequent sub-frame, the sleep indicationsignal transmitted in the sleep control channel 700 will inform thecommunications device to power down its receiver because it does notneed to receive the entire signals transmitted in the narrow bandcontrol channel 600.

As will be appreciated therefore a power saving to the communicationsterminals is provided, the power saving offered depending on theposition in time of the sleep control region, and the width of theregion conveying the SIS. In the example given, if the wide band controlregion is three symbols wide, the communications device can sleep afterfour out of the fourteen OFDM symbols in a sub-frame.

A further example embodiment is shown in FIG. 8 which corresponds tothat shown in FIG. 7 except that the second narrow band control channelis formed of first and second parts 801, 802 which are disposed atdifferent frequencies within a frequency range of the host carrier. Thefirst and second parts of the narrow band control channel extend overthe sub-frame from the first wide band control channel 300. However, asshown in this example the SIS is transmitted in first and second partsof the sleep control channel regions 804, 806 which allows somefrequency diversity to be afforded for improving a likelihood ofcorrectly receiving the SIS at the communications terminals. As with theexample shown in FIG. 7 if an SIS is transmitted in the sleep controlchannel from the first and second parts 804, 806 in which one or morecommunications devices are identified using an appropriate identifierthen the communications devices do not need to receive the signallinginformation for the remainder of the narrow band control channel 801,802 and accordingly can power down their receivers.

In general, the total sleep control channel region may be dividedunequally between the multiple parts of the distributed narrow bandcontrol region depending on such factors as their respective resourceavailability, and need not extend across the entire frequency width of agiven part of the control region. The sleep control channel region mayalso be interleaved across such a distributed narrow band controlregion. The manner of such division and interleaving could be defined inspecifications or configured semi-statically by RRC.

As will be appreciated the structure shown in FIG. 8 is analogous to adistributed EPDCCH whereas embodiments until now have had a narrow bandcontrol region analogous to a localised EPDCCH. Nevertheless, themethods of previous embodiments apply to this embodiment also.

Sleep Indication Signal Format

As explained above, in one example the SIS may include sufficientcapacity for communicating identifiers of communications devicesconveyed in a 24-bit field, which may be referred to as an SIS identity(SISI). The SISI could be configured at the communications devices viaRRC at initial setup. Preferably, SISIs would be shorter than 24 bits sothat multiple devices can be sent an SIS in one sub-frame. For example,if an SISI for a communications device is 6 bits long, then the SIS canbe divided into four non-overlapping regions, each 6 bits long, thatcommunications devices are expected to search for their SISI. In thisway, 2⁶=64 communications devices can be provided with a SISI pervirtual carrier, and 4 can be given a sleep indication per sub-frame pervirtual carrier. Other combinations of SISI length and division of the24 bit sleep control channel region would produce other supportedcommunications device quantities (for example, SISI could be 8 bitslong, supporting 256 communications devices, with 3 able to receive asleep indication per virtual carrier per sub-frame).

Variable SISI Length

In another example similar to the first, the length of a SISI isadjusted by the eNB 101 to account for how often the communicationsdevice is likely to receive a SIS. This adjustment could be for exampleon the basis of the down link traffic profile for the communicationsdevice 104 over some time history, or by network configuration accordingto the application. A communications device 104 which is relatively morelikely to receive a SIS could receive a shorter SISI so that it can besignalled more often while still leaving space in the sleep controlchannel region for other communications devices to also receive SIS inthe same sub-frame. If the SISI is RRC configurable, then it can bealtered as the network detects that a traffic profile of acommunications device is changing, or by an indication from theapplication that there has been a change in the communications device'slikely needs.

Sequential Offset C-RNTI as SISI

In further example, instead of introducing a new SISI of previousembodiments, the SISI is the Cell-Radio Network Temporary Indentifier(C-RNTI) instead. This reduces the amount of information that must betransferred over RRC. However, the C-RNTI is always 16 bits long so, inthe example of the sleep control channel region being at most 24 bitslong, only one communications device could be signalled per sub-frame.Therefore, in an example embodiment, the network chooses C-RNTIs suchthat their binary bit patterns are nested. A communications device thenneed only be configured with the offset within the sleep control channelregion at which it should begin trying to decode for its C-RNTI. Forexample, if the following 3 C-RNTIs, expressed in hexadecimal thenbinary, are used:

communications device0 C-RNTI: 0x66E9=0 1 1 0 0 1 1 0 1 1 1 0 1 0 0 1

communications device1 C-RNTI: 0xCDD3=1 1 0 0 1 1 0 1 1 1 0 1 0 0 1 1

communications device2 C-RNTI: 0x9BA7=1 0 0 1 1 0 1 1 1 0 1 0 0 1 1 1

SIS transmitted=0 1 1 0 0 1 1 0 1 1 1 0 1 0 0 1 1 1

As such, all three communications devices' C-RNTIs can be embeddedwithin 18 bits and clearly six further communications devices could besimilarly nested. A communications device need only be configured, e.g.by RRC, such that it should decode in the sleep control channel regionstarting from position 0, 1, or 2 (counting from the left-most bit) inthe example. The particular method of choosing C-RNTIs to be nested toallow their multiplexing within a particular resource provides anadvantage in that by nesting the C-RNTI's for communications devices anRRC configuration need convey only the bit-wise offset in the sleepcontrol channel region from where the communications device should begindecoding for its own C-RNTI.CDM of SISI

In a further example, more than one SISI may be transmitted in the sleepcontrol channel region 700. The multiple SISIs are each scrambled with adifferent code such that interference between the multiple transmissionsis below a suitable threshold after decoding at the communicationsdevice. For example, the orthogonal cover codes (OCC) or Walsh-Hadamardsequences used elsewhere in LTE could be used for this purpose also. Inone implementation, the same un-scrambled SISI could then be configuredfor multiple communications devices, and communications devices are thendistinguished in the code domain, provided sufficient codeorthogonality. A communications device would need to be configured withwhich scrambling code it should use to de-scramble the sleep controlchannel region, and also which un-scrambled SISI it can react to. Thelatter could be provided by one of the other embodiments explainedabove, notably the offset of the C-RNTI example, which couldsignificantly increase the capacity of the sleep control channel region.The list of scrambling codes could be provided in specifications andsignalled via RRC.

Group-Sleep Indication Signal

A further example corresponds to the example embodiments presentedabove, but a single SISI can apply to more than one communicationsdevice at a time. For example this could be by RRC signalling of theSISI as in the first example above (where the SISI is independent ofother identities held by the communications device). In this case, agroup of communications devices all with the same identity can beallowed to sleep in a sub-frame, thus further increasing the capacity ofthe sleep control channel region 700.

Sleep Control Channel Region

In general, the sleep control channel region 700 could convey additionaldata as well as the SISI(s) for that sub-frame. This could require moreresources to be reserved. For example, it may be appropriate for theregion to extend across the bandwidth of the virtual carrier and carrySISI(s) as well as format indications regarding the narrow band controlregion, for a similar purpose as PCFICH in Rel-8.

As explained above in one example the second narrow band communicationschannel is an EPDCCH 600 and the first wide band control channel is aPDCCH 300. As will be appreciated conventional communications deviceswhich have a capability for receiving signals from the frequency rangeof the host carrier may also be configured to receive signallinginformation from the narrow band control channel 600 because the narrowband control channel affords some advantages in respect of a reductionof co-channel interference and a beam forming capability. Accordingly inone example it may be desired that the sleep control channel region 700for transmitting the SIS does not form part of the narrow band controlchannel 600. Such an arrangement is shown in FIG. 9.

In FIG. 10 the sleep control channel 900 which is transmitted as part ofthe shared resources of the virtual carrier 540 is transmitted in a waythat it does not use any part of the narrow band control channel 600.Accordingly, the narrow band control channel 600 can be used tocommunicate signalling information such as resource allocation messagesto both full capability communications devices and second reducedcapability communications devices which only operate within thefrequency range of the virtual carrier 501.

Some example embodiments can provide an arrangement in which reducedcapability communications devices of a second type exist within a cellserved by a base station with full capability devices of a first typeand in which both a wide band control channel region 300 and a narrowband control channel region 600 is provided by a wireless accessinterface to the first and second types of communications devices. Thebase station can arrange for the wireless access interface to locate thenarrow band control region 600 within a second frequency range providinga virtual carrier which exists within a host carrier covering a firstfrequency range, the first frequency range including the secondfrequency range. Thus, a scheduler for example of the base station isadapted to locate the narrow band control channel 600 (EPDCCH) as partof a virtual carrier within the second frequency range so thatcommunications devices of the second type are able to receive controlinformation granting access to communications resources from the narrowband control channel 600 as well as devices of the first type also beinggranted access to communications resources from the narrow band controlchannel 600. However, as a result of the reduced capability of thecommunications devices of the second type, the narrow band controlchannel grants access to communications resources only within the secondfrequency range whereas full capability devices of the first type may begranted access to shared resources within the first frequency range ofthe host carrier. Accordingly, the co-existence of full capabilitycommunications devices of the first type with reduced capabilitycommunications devices of the second type which receive controlinformation granting access to communications resources from the samenarrow band control channel provides an arrangement which efficientlyuses communications resources available to the communications systems.

An arrangement shown in FIG. 9 provides an example in which a sleepcontrol channel region 700, for communicating SIS(s), is formed in aregion of the virtual carrier, which would otherwise form part of boththe second narrow band control channel 600 and the shared resources 540of the virtual carrier 501. As will be appreciated for the example shownin FIG. 9, full capability communications devices will need to beadapted to receive the SIS or to only begin to receive signallinginformation from the second narrow band control channel 600 startingafter the sleep control channel region 700 containing the SIS.

According to an example shown in FIG. 10, the narrow band controlchannel 600 is shared by communications devices able to use the fullextent of the host carrier as well as reduced capability narrowbandcommunications devices confined to the virtual carrier 501. This controlregion could be an EPDCCH as being defined by 3GPP for Rel-11.Therefore, in this embodiment, the sleep control channel region 700 isinserted at the start of the virtual carrier shared resources 540 butonly on subcarriers not used by EPDCCH so that non-virtual carriercommunications devices are not disturbed by its presence. As with theexample illustrated in FIG. 9 the sleep control channel region 700 couldcontain additional data beyond the SISI(s) if its resource is largeenough to do so. For example, it could provide information to virtualcarrier communications devices regarding the location of the (shared)control region, for virtual carrier communications devices which are notincluded in the sleep indication in a given sub-frame.

Example Architecture

FIG. 11 provides a schematic diagram showing part of an adapted LTEmobile communications system. The system includes an adapted enhancedNode B (eNB) 1401 connected to a core network 1408 which communicatesdata to a plurality of conventional LTE devices 1402 and reducedcapability devices 1403 within a coverage area (i.e. cell) 1404. Each ofthe reduced capability devices 1403 has a transceiver unit 1405 whichincludes a receiver unit capable of receiving data across a reducedbandwidth and a transmitter unit capable of transmitting data across areduced bandwidth (or full bandwidth of an uplink carrier supported bythe eNB 1401) when compared with the capabilities of the transceiverunits 1406 included in the conventional LTE devices 1402.

The adapted eNB 1401 is arranged to transmit downlink data using asub-frame structure that includes a virtual carrier as described abovefor example with reference to FIGS. 4 to 10. The reduced capabilitydevices 1403 are thus able to receive and transmit data using the uplinkand downlink virtual carriers as described above.

As has been explained above, because the reduced complexity devices 1403receive data across a reduced bandwidth downlink virtual carriers, thecomplexity, power consumption and cost of the transceiver unit 1405needed to receive and decode downlink data and to encode and transmituplink data is reduced compared to the transceiver unit 1406 provided inthe conventional LTE devices.

When receiving downlink data from the core network 1408 to betransmitted to one of the devices within the cell 1404, the adapted eNB1401 is arranged to determine if the data is bound for a conventionalLTE device 1402 or a reduced capability device 1403. This can beachieved using any suitable technique. For example, data bound for areduced capability device 1403 may include a virtual carrier flagindicating that the data must be transmitted on the downlink virtualcarrier. If the adapted eNB 1401 detects that downlink data is to betransmitted to a reduced capability device 1403, an adapted schedulingunit 1409 included in the adapted eNB 1401 ensures that the downlinkdata is transmitted to the reduced capability device in question on thedownlink virtual carrier. In another example the network is arranged sothat the virtual carrier is logically independent of the eNB. Moreparticularly the virtual carrier is arranged to appear to the corenetwork as a distinct cell. From the perspective of the core network itis not known that the virtual carrier is physically co-located with, orhas any interaction with, the host carrier of the cell. Packets arerouted to/from the virtual carrier just as they would be for any normalcell.

In another example, packet inspection is performed at a suitable pointwithin the network to route traffic to or from the appropriate carrier(i.e. the host carrier or the virtual carrier).

In yet another example, data from the core network to the eNB iscommunicated on a specific logical connection for a specificcommunications device. The eNB is provided with information indicatingwhich logical connection is associated with which communications device.Information is also provided at the eNB indicating which communicationsdevices are reduced capability devices and which are conventional LTEdevices. This information could be derived from the fact that a reducedcapability device would initially have connected using virtual carrierresources. In other examples reduced capability devices are arranged toindicate their capability to the eNB during the connection procedure.Accordingly the eNB can map data from the core network to a specificcommunications device based on whether the communications device is areduced capability device or an LTE device.

When scheduling resources for the transmission of uplink data, theadapted eNB 1401 is arranged to determine if the device to be scheduledresources is a reduced capability device 1403 or a conventional LTEdevice 1402. In some examples this is achieved by analysing the randomaccess request transmitted on the PRACH using the techniques todistinguish between a virtual carrier random access request and aconventional random access request as described above. In any case, whenit has been determined at the adapted eNB 1401 that a random accessrequest has been made by a reduced capability device 1402, the adaptedscheduler 1409 is arranged to ensure that any grants of uplinkcommunications resource elements are within the virtual uplink carrier.

The embodiments described above are arranged to allow microsleep-likebehaviour of communications devices in a virtual carrier system. Thiscan permit power savings to be obtained at a connected-modecommunications device by abandoning the processing of a sub-frame inwhich there will be no down link or up link resource assignment relevantto that communications device. It allows the network to signal thisinformation to multiple communications devices in one sub-frame withminimal DL control region resource loss. The embodiments have beendescribed with reference to LTE, but may also be applicable in otherwireless communication systems, such as UMTS, as well as in both FDD andTDD systems.

SUMMARY

A flow diagram providing an illustration of a mobile communicationsnetwork and a communications terminal operating in accordance with anexample embodiment is shown in FIG. 12, which is summarised as follows:

S1: One or more network elements, such as base stations or eNBs, of amobile communications network are configured to provide a wirelessaccess interface for communicating data to and/or from communicationsdevices.

S2: The wireless access interface provided by the network elements isarranged to include a plurality of time divided sub-frames, eachsub-frame including the plurality of communications resource elements.

S4: The wireless access interface provided by the network elements isarranged to include in the sub-frames a first wideband control channelhaving a bandwidth corresponding substantially to a bandwidth of thewireless access interface

S6: Communicate first signalling information to one or more of thecommunications devices.

S8: The wireless access interface provided by the network elements isarranged to include, in the sub-frames, a second narrow band controlchannel. The second narrow band control channel is configured to have abandwidth which is less than the first wideband control channel and aduration within the sub-frame which is greater than a duration of thefirst wideband control channel within the sub-frame.

S10: Communicate second signalling information to one or more of thecommunications devices in the second narrow band control channel, thesecond signalling information, being for example resource allocationmessages for allocating resources to the communications devices.

S12: Transmit a sleep indication signal (SIS) to one or more of thecommunications devices, the SIS indicating to the one or more of thecommunications devices that the communications devices do not need toreceive the second signalling information from the second narrow bandcontrol channel, or in other words that there is no signallinginformation for the one or more communications devices in the secondnarrow band communications channel. Alternatively the SIS could includean indication of one or more of the communications devices which are toreceive signalling information in the second narrow band controlchannel.

S14: A communications device identifies its identifier in the SIS andreduces power to at least part of its receiver, thereby saving power, ifthe SIS represents and indication that there is no signallinginformation in the second narrow band communications channel for thecommunications device.

According to one example there is provided a method of transmitting datato and/or receiving data from communications devices using a mobilecommunications network. The method comprising:

providing a wireless access interface, using one or more networkelements for communicating data to and/or from the communicationsdevices, the wireless access interface providing a plurality ofcommunications resource elements across a first frequency range andproviding a plurality of communications resource elements within asecond frequency range which is within and smaller than the firstfrequency range, wherein the wireless access interface includes

a plurality of time divided sub-frames, each sub-frame including theplurality of communications resource elements of the first frequencyrange and the plurality of the communications resource elements of thesecond frequency range, and at least one of the each sub-frames includes

a first wideband control channel in a part of the sub-frame having abandwidth corresponding substantially to the first frequency range forcommunicating first signalling information to one or more of thecommunications devices, and at least one of the sub-frames includes

a second narrow band control channel in a second part of the sub-frameand having a bandwidth which is less than the first wideband controlchannel and a duration of the second narrow band control channel withinthe sub-frame is greater than a duration of the first wideband controlchannel within the sub-frame, the second narrow band control channelbeing configured for communicating second signalling information to oneor more of the communications devices, and

transmitting a sleep indication signal to one or more of thecommunications devices, the sleep indication signal indicating to theone or more of the communications devices that the communicationsdevices do not need to receive the second signalling information fromthe second narrow band control channel.

As may be appreciated from the above explanation there is an evidentlimit on how many communications devices can receive an SIS in asub-frame. Other communications devices with no resource allocation willhave to decode the entire sub-frame as per normal operation in such avirtual carrier.

Various modifications can be made to examples of the present disclosure.Embodiments of the present disclosure have been defined largely in termsof reduced capability devices transmitting data via a virtual carrierinserted in a conventional LTE based host carrier. However, it will beunderstood that any suitable device can transmit and receive data usingthe described virtual carriers for example devices which have the samecapability as a conventional LTE type device or devices which haveenhanced capabilities.

Furthermore, it will be understood that the general principle ofinserting a virtual carrier on a subset of uplink or downlink resourcescan be applied to any suitable mobile telecommunication technology andneed not be restricted to systems employing an LTE based radiointerface.

Various further aspects and features of the present technique aredefined in the following numbered clauses:

1. A communications device for transmitting data to or receiving datafrom a mobile communications network, the mobile communications networkproviding a wireless access interface for the communications device, thecommunications device comprising:

a transmitter unit adapted to transmit data to the mobile communicationsnetwork via the wireless access interface provided by one or morenetwork elements of the mobile communications network, and

a receiver unit adapted to receive data from the mobile communicationsnetwork via the wireless access interface provided by the one or morenetwork elements of the mobile communications network, the wirelessaccess interface providing a plurality of communications resourceelements across a first frequency range, wherein the wireless accessinterface includes

a plurality of time divided sub-frames, and at least one of thesub-frames includes a first wideband control channel in a part of thesub-frame for communicating first signalling information to thecommunications device, and at least one of the sub-frames includes

a second narrow band control channel in a second part of the sub-frameand having a bandwidth which is less than the first wideband controlchannel and a duration of the second narrow band control channel withinthe sub-frame is greater than a duration of the first wideband controlchannel within the sub-frame, the second narrow band control channelbeing configured for communicating second signalling information to thecommunications device, and the receiver unit is configured

to receive a sleep indication signal, the sleep indication signalindicating to the communications device that the communications devicedoes not need to receive the second signalling information from thesecond narrow band control channel, and

in response to receiving the sleep indication signal, to stop receivingthe second signalling information from the second narrow band controlchannel.

2. A communications device according to clause 1, wherein in response toreceiving the sleep indication signal, the receiver unit is configurednot to receive the signalling information for one or more of thesub-frames.

3. A communications device according to clause 1 or 2, wherein the sleepindication signal is received by the communications device at a timewithin the sub-frame which is closer to a start of the sub-frame than anend of the sub-frame.

4. A communications device according to clause 3, wherein the sleepindication signal is received by the communications device at a timewithin the sub-frame which is close to a start of the second narrow bandcontrol channel.

5. A communications device according to any preceding clause, whereinthe sleep indicator signal includes an identifier, and the receiver isconfigured to detect an identifier corresponding to the communicationsdevice in the sleep indicator indicating to the communications devicethat the communications devices identified by the identifier does notneed to receive the second signalling information.

6. A communications device according to clause 5, wherein the identifierof the sleep indicator signal provides an indication of one of thegroups of communications devices which do not need to receive the secondsignalling information from the second narrow band control channel.

7. A communications device according to clause 5, wherein the identifierof the sleep indicator field is configured to provide a radio networkidentifier number allocated to the communications device by the network.

8. A communications device according to any preceding clause, whereinthe sleep indicator signal is received by the communications device froma third control channel, at least part of the third control channelbeing formed from a part of the second narrow band control channel.

9. A communications device according to clause 8, wherein the wirelessaccess network provides a plurality of communications resource elementswithin a second frequency range which is within and smaller than thefirst frequency range and the third control channel is formed from theplurality of communications resource elements within the secondfrequency range.

10. A communications device according to clause 8, wherein the secondnarrow band control channel is formed within the plurality ofcommunications resource elements of the second frequency range, and thethird control channel is formed within the plurality of communicationsresource elements of the second frequency range.

11. A communications device according to clause 10, wherein the secondnarrow band control channel and the third control channel do not shareany of the plurality of communications resource elements within thesecond frequency range.

12. A communications device according to any of clauses 9 to 11, whereinthe receiver unit is configured to provide a reduced bandwidthcapability, the communications device being a reduced capabilitycommunications device, the reduced capability receiver being configuredto receive signals transmitted only via the plurality of communicationsresource elements within the second frequency range, and the secondsignalling information communicated in the second narrow band controlchannel includes resource allocation messages for allocating to thecommunications device one or more of the plurality of communicationresources of the second frequency range, wherein the transmitter unittransmits data in the one or more allocated resources of the secondfrequency range or the receiver unit receives data from the one or moreallocated resources of the second frequency range.

13. A method of transmitting data to or receiving data from a mobilecommunications network using a communications device, the mobilecommunications network providing a wireless access interface for thecommunications device, the method comprising:

transmitting data to the mobile communications network via the wirelessaccess interface provided by one or more network elements of the mobilecommunications network, and/or

receiving data from the mobile communications network via the wirelessaccess interface provided by the one or more network elements of themobile communications network, the wireless access interface providing aplurality of communications resource elements across a first frequencyrange, wherein the wireless access interface includes

a plurality of time divided sub-frames, and at least one of thesub-frames includes

a first wideband control channel in a part of the sub-frame forcommunicating first signalling information to the communications device,and at least one of the sub-frames includes

a second narrow band control channel in a second part of the sub-frameand having a bandwidth which is less than the first wideband controlchannel and a duration of the second narrow band control channel withinthe sub-frame is greater than a duration of the first wideband controlchannel within the sub-frame, the second narrow band control channelbeing configured for communicating second signalling information to thecommunications device, and the method comprises

receiving a sleep indication signal, the sleep indication signalindicating to the communications device that the communications devicedoes not need to receive the second signalling information from thesecond narrow band control channel, and

in response to receiving the sleep indication signal, not receiving thesecond signalling information from the second narrow band controlchannel.

14. A method according to clause 1, wherein the response to receivingthe sleep indication signal, includes not receiving the signallinginformation for one or more of the sub-frames.

15. A method according to clause 13 or 14, wherein the receiving thesleep indication signal, includes receiving the sleep indication signalby the communications device at a time within the sub-frame which iscloser to a start of the sub-frame than an end of the sub-frame.

16. A method according to clause 15, wherein the receiving the sleepindication signal, includes receiving the sleep indication signal by thecommunications device at a time within the sub-frame which is close to astart of the second narrow band control channel.

17. A method according to any of clauses 13 to 16, wherein the sleepindicator signal includes an identifier, and the method includesdetecting an identifier corresponding to the communications device inthe sleep indicator, the identifier indicating to the communicationsdevice that the communications devices identified by the identifier doesnot need to receive the second signalling information.

18. A method according to clause 17, the method comprising

providing with the identifier of the sleep indication signal anindication of one of a plurality of groups into which the communicationsdevices are divided, which communications devices of the group do notneed to receive the second signalling information from the second narrowband control channel, and

identifying from the identifier of the sleep indication signal that thecommunications device does not need to receive the second signallinginformation from the second narrow band control channel based on theidentified group.

19. A method according to clause 17, wherein the identifier of the sleepindicator field is configured to provide a radio network identifiernumber allocated to the communications device by the network.

20. A method according to any of clauses 13 to 19, wherein the receivingthe sleep indication signal, includes receiving the sleep indicationsignal by the communications device from a third control channel, atleast part of the third control channel being formed from a part of thesecond narrow band control channel.

21. A method according to clause 20, wherein the wireless access networkprovides a plurality of communications resource elements within a secondfrequency range which is within and smaller than the first frequencyrange and the third control channel is formed from the plurality ofcommunications resource elements within the second frequency range.

22. A method according to clause 20, wherein the second narrow bandcontrol channel is formed within the plurality of communicationsresource elements of the second frequency range, and the third controlchannel is formed within the plurality of communications resourceelements of the second frequency range.

23. A method according to clause 22, wherein the second narrow bandcontrol channel and the third control channel do not share any of theplurality of communications resource elements within the secondfrequency range.

24. A method according to any of clauses 21 to 23, comprising

providing the communications device with a reduced bandwidth capability,the communications device being a reduced capability communicationsdevice, the receiving the data from the mobile communications networkvia the wireless access interface comprising

receiving the data using the reduced capability receiver by receivingsignals transmitted only via the plurality of communications resourceelements within the second frequency range, and the second signallinginformation communicated in the second narrow band control channelincludes resource allocation messages for allocating to thecommunications device one or more of the plurality of communicationresources of the second frequency range, wherein the transmitting thedata includes transmitting the data in the one or more allocatedresources of the second frequency range or the receiving the dataincludes receiving the data from the one or more allocated resources ofthe second frequency range.

The invention claimed is:
 1. A communications device for transmittingdata to or receiving data from a mobile communications network, themobile communications network providing a wireless access interface forthe communications device, the communications device comprising: atransmitter configured to transmit data to the mobile communicationsnetwork via the wireless access interface provided by one or morenetwork elements of the mobile communications network, and a receiverconfigured to receive data from the mobile communications network viathe wireless access interface provided by the one or more networkelements of the mobile communications network, the wireless accessinterface providing a plurality of communications resource elementsacross a first frequency range, wherein the wireless access interfaceincludes a plurality of time divided sub-frames, and at least one of thesub-frames includes a first wideband control channel in a part of thesub-frame for communicating first signaling information to thecommunications device, and at least one of the sub-frames includes asecond narrow band control channel in a second part of the sub-frame andhaving a bandwidth which is less than the first wideband control channeland a duration of the second narrow band control channel within thesub-frame is greater than a duration of the first wideband controlchannel within the sub-frame, the second narrow band control channelbeing configured for communicating second signaling information to thecommunications device, and the receiver is configured to receive a sleepindication signal, the sleep indication signal indicating to thecommunications device that the communications device does not need toreceive the second signaling information from the second narrow bandcontrol channel, and in response to receiving the sleep indicationsignal, stop receiving the second signaling information from the secondnarrow band control channel.
 2. The communications device of claim 1,wherein in response to receiving the sleep indication signal, thereceiver is configured not to receive the signaling information for oneor more of the sub-frames.
 3. The communications device of claim 1,wherein the sleep indication signal is received by the communicationsdevice at a time within the sub-frame which is closer to a start of thesub-frame than an end of the sub-frame.
 4. The communications device ofclaim 3, wherein the sleep indication signal is received by thecommunications device at a time within the sub-frame which is close to astart of the second narrow band control channel.
 5. The communicationsdevice of claim 1, wherein the sleep indicator signal includes anidentifier, and the receiver is configured to detect an identifiercorresponding to the communications device in the sleep indicatorindicating to the communications device that the communications devicesidentified by the identifier does not need to receive the secondsignaling information.
 6. The communications device of claim 5, whereinthe identifier of the sleep indicator signal provides an indication ofone of the groups of communications devices which do not need to receivethe second signaling signalling information from the second narrow bandcontrol channel.
 7. The communications device of claim 5, wherein theidentifier of the sleep indicator field is configured to provide a radionetwork identifier number allocated to the communications device by thenetwork.
 8. The communications device of claim 1, wherein the sleepindicator signal is received by the communications device from a thirdcontrol channel, at least part of the third control channel being formedfrom a part of the second narrow band control channel.
 9. Thecommunications device of claim 8, wherein the wireless access networkprovides a plurality of communications resource elements within a secondfrequency range which is within and smaller than the first frequencyrange and the third control channel is formed from the plurality ofcommunications resource elements within the second frequency range. 10.The communications device of claim 8, wherein the second narrow bandcontrol channel is formed within the plurality of communicationsresource elements of the second frequency range, and the third controlchannel is formed within the plurality of communications resourceelements of the second frequency range.
 11. The communications device ofclaim 10, wherein the second narrow band control channel and the thirdcontrol channel do not share any of the plurality of communicationsresource elements within the second frequency range.
 12. Thecommunications device of claim 9, wherein the receiver is configured toprovide a reduced bandwidth capability, the communications device beinga reduced capability communications device, the reduced capabilityreceiver being configured to receive signals transmitted only via theplurality of communications resource elements within the secondfrequency range, the second signaling information communicated in thesecond narrow band control channel includes resource allocation messagesfor allocating to the communications device one or more of the pluralityof communication resources of the second frequency range, and thetransmitter transmits data in the one or more allocated resources of thesecond frequency range or the receiver receives data from the one ormore allocated resources of the second frequency range.
 13. A method oftransmitting data to or receiving data from a mobile communicationsnetwork using a communications device, the mobile communications networkproviding a wireless access interface for the communications device, themethod comprising: transmitting data to the mobile communicationsnetwork via the wireless access interface provided by one or morenetwork elements of the mobile communications network, and/or receivingdata from the mobile communications network via the wireless accessinterface provided by the one or more network elements of the mobilecommunications network, the wireless access interface providing aplurality of communications resource elements across a first frequencyrange, wherein the wireless access interface includes a plurality oftime divided sub-frames, and at least one of the sub-frames includes afirst wideband control channel in a part of the sub-frame forcommunicating first signaling information to the communications device,and at least one of the sub-frames includes a second narrow band controlchannel in a second part of the sub-frame and having a bandwidth whichis less than the first wideband control channel and a duration of thesecond narrow band control channel within the sub-frame is greater thana duration of the first wideband control channel within the sub-frame,the second narrow band control channel being configured forcommunicating second signaling information to the communications device,and the method comprises receiving a sleep indication signal, the sleepindication signal indicating to the communications device that thecommunications device does not need to receive the second signalinginformation from the second narrow band control channel, and in responseto receiving the sleep indication signal, not receiving the secondsignaling information from the second narrow band control channel. 14.The method of claim 13, wherein the response to receiving the sleepindication signal, includes not receiving the signaling information forone or more of the sub-frames.
 15. The method of claim 13, wherein thereceiving the sleep indication signal includes receiving the sleepindication signal by the communications device at a time within thesub-frame which is closer to a start of the sub-frame than an end of thesub-frame.
 16. The method of claim 15, wherein the receiving the sleepindication signal includes receiving the sleep indication signal by thecommunications device at a time within the sub-frame which is close to astart of the second narrow band control channel.
 17. The method of claim13, wherein the sleep indicator signal includes an identifier, and themethod includes detecting an identifier corresponding to thecommunications device in the sleep indicator, the identifier indicatingto the communications device that the communications devices identifiedby the identifier does not need to receive the second signalinginformation.
 18. The method of claim 17, the method comprising:providing with the identifier of the sleep indication signal anindication of one of a plurality of groups into which the communicationsdevices are divided, which communications devices of the group do notneed to receive the second signaling information from the second narrowband control channel; and identifying from the identifier of the sleepindication signal that the communications device does not need toreceive the second signaling information from the second narrow bandcontrol channel based on the identified group.
 19. The method of claim17, wherein the identifier of the sleep indicator field is configured toprovide a radio network identifier number allocated to thecommunications device by the network.
 20. The method of claim 13,wherein the receiving the sleep indication signal includes receiving thesleep indication signal by the communications device from a thirdcontrol channel, at least part of the third control channel being formedfrom a part of the second narrow band control channel.
 21. The method ofclaim 20, wherein the wireless access network provides a plurality ofcommunications resource elements within a second frequency range whichis within and smaller than the first frequency range, and the thirdcontrol channel is formed from the plurality of communications resourceelements within the second frequency range.
 22. The method of claim 20,wherein the second narrow band control channel is formed within theplurality of communications resource elements of the second frequencyrange, and the third control channel is formed within the plurality ofcommunications resource elements of the second frequency range.
 23. Themethod of claim 22, wherein the second narrow band control channel andthe third control channel do not share any of the plurality ofcommunications resource elements within the second frequency range. 24.The method of claim 21, wherein the communications device has a reducedbandwidth capability, the communications device being a reducedcapability communications device, the receiving the data from the mobilecommunications network via the wireless access interface comprises:receiving the data using the reduced capability receiver by receivingsignals transmitted only via the plurality of communications resourceelements within the second frequency range, and the second signalinginformation communicated in the second narrow band control channelincludes resource allocation messages for allocating to thecommunications device one or more of the plurality of communicationresources of the second frequency range, and the transmitting the dataincludes transmitting the data in the one or more allocated resources ofthe second frequency range or the receiving the data includes receivingthe data from the one or more allocated resources of the secondfrequency range.